Hi,

What is benefit from setting in 'action' a reference to a template, which specifies the structure of the message to be sent by the SUT, i.e. what is difference in:

action("MyTemplate");
action(MyTemplate);

In both cases there is no information e.g. on which port it should be sent.
In the first case it may be extended, in the second case it is not possible.
Are the second alternative only for keeping harmony with TTCN-2 IMPLICIT SEND statement?

This is from clause 15.9.6 "The IMPLICIT SEND event" from TTCN-2 specification:
"There is no specification of what is done to the IUT to trigger this reaction, only a specification of the required reaction itself; the specified ASP or PDU is to be sent by the IUT on the indicated PCO. IUT can take place of the PCO identifier if there is no ambiguity (only one PCO exists for example)."

In TTCN-2 the usage is e.g. <IUT ! CR> or <PCO_Identifier ! CR> when there is any ambiguity which PCO should be used:

661 ImplicitSend ::= "<" (IUT | PCO_Identifier | FormalParIdentifier) "!" (ASP_Identifier | PDU_Identifier) ">"
/* STATIC SEMANTICS - ImplicitSend shall not be used unless the test method being used is one of the Remote Test Methods. */

/* STATIC SEMANTICS - FormalParIdentifier shall resolve to a PCO_Identifier.*/


I am not sure but maybe in TTCN-3 it should be used consequently, with a specification on which system port MyTemplate should be sent?

EXAMPLE:
action(MyTemplate); // for only one port used
MyPort.action(MyTemplate); // for more ports used, to avoid ambiguity,

BR,
Mariusz Kupiec